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首页> 外文期刊>Zeitschrift fur Naturforschung, B. A Journal of Chemical Sciences >A conformational study of 5,10,15,20-tetraalkyl-22H(+),24H(+) porphyrindiium salts (dication salts)
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A conformational study of 5,10,15,20-tetraalkyl-22H(+),24H(+) porphyrindiium salts (dication salts)

机译：5,10,15,20-四烷基-22H（+），24H（+）卟啉二盐（支配盐）的构象研究

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摘要

N-protonation of 5,10,15,20-tetraalkylporphyrins with n-butyl, isobutyl, isopropyl, 1-ethyl-propyl or tert-butyl substituents yields the respective 22,24-dihydroporphyrins (22H(+),24H(+)-porphyrindiium salts) that exhibit highly nonplanar conformations. Depending on the steric demand of the meso substituents, the free base porphyrins have planar to moderately ruffled macrocycles (primary or secondary alkyl residues) or are severely ruffled (tertiary alkyl residues). X-ray crystallographic studies show that protonation of porphyrins with n-Bu (2), i-Pr (3) or EtPr (4) substituents leads to steric congestion of the core resulting in symmetric, saddle distorted macrocycles as evidenced by average displacements of the Cb positions from the mean plane ranging from 0.79 to 1.01 A. The structures observed for these porphyrin diacids are very similar in distortion mode and degree of nonplanarity to 5,10,15,20-tetraaryl-22H(+),24H(+)-porphyrindiium salts and to 2,3,7,8,12,13,17,18-octaalkyl-5,10,15,20-tetraaryl-porphyrins. In contrast, protonation of the highly ruffled 5,10,15,20-tetrakis(tert-butyl)porphyrin results in a switch of the conformational distortion mode. The dication 6 shows both saddle distortion (C-b displacements similar to 1.3 Angstrom) and ruffling of the macrocycle (C-m displacements of approx. 0.48 Angstrom). Thus, the need to accomodate four N-H units in the porphyrin core with its associated out-of-plane tilting of the pyrrole rings and the steric strain induced at the meso carbon atoms results in a highly nonplanar porphyrin with mixed distortion modes. [References: 45]
机译：用正丁基，异丁基，异丙基，1-乙基丙基或叔丁基取代基对5、10、15、20-四烷基卟啉进行N质子化反应分别得到22,24-二氢卟啉（22H（+），24H（+） -卟啉盐）显示高度非平面构象。取决于内消旋取代基的空间需求，游离碱卟啉具有平面至中度起皱的大环（伯或仲烷基残基）或被重度起皱（叔烷基残基）。 X射线晶体学研究表明，带有n-Bu（2），i-Pr（3）或EtPr（4）取代基的卟啉的质子化导致核的空间拥塞，导致对称的鞍形扭曲大环，由Cb的平均平面范围为0.79至1.01A。观察到的这些卟啉二酸的结构在畸变模式和非平面度上与5,10,15,20-tetraaryl-22H（+），24H（+ ）-卟啉二鎓盐和2,3,7,8,12,13,17,18-八烷基-5,10,15,20-四芳基-卟啉。相反，高度起皱的5,10,15,20-四（叔丁基）卟啉的质子化导致构象变形模式的转换。标记6既显示了鞍形失真（类似于1.3埃的C-b位移），也显示了大周期的波动（近似0.48埃的C-m位移）。因此，需要使卟啉核中的四个N-H单元具有吡咯环的平面外倾斜和在介孔碳原子处诱导的空间应变，从而导致具有混合畸变模式的高度非平面的卟啉。 [参考：45]

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